Clutch release bearing and rolling bearing for a clutch release bearing

ABSTRACT

A clutch release bearing for a motor vehicle includes a thrust element having an axial axis, a guide element in the form of a tubular bushing that supports the thrust element, and a self-aligning sleeve including an annular body and a plurality of radial ribs each having a free end. The plurality of ribs extend towards the guide element from the annular body. The free ends of at least a first set of the plurality of radial ribs radially contact the cylindrical external surface of the bushing, and the bushing includes at least one opening in a cylindrical external surface of the bushing that is configured to receive one of the plurality of radial ribs.

CROSS-REFERENCE

This application claims priority to French patent application no.2007764 filed on Jul. 23, 2020, the contents of which are fullyincorporated herein by reference.

TECHNOLOGICAL FIELD

The present disclosure is directed to the field of clutch releasebearings and to rolling bearings used in clutch release bearings.

BACKGROUND

Generally, clutch release bearings comprise a thrust element configuredto cooperate with a clutch diaphragm, the thrust element being mountedon an operating element capable of moving translationally under theaction of a control member, such as a clutch release fork or a hydrauliccontrol piston. The thrust element is additionally able to move radiallywith respect to the operating element within the necessary limits ofself-aligning of the thrust element with respect to the diaphragm.

In a known manner, the thrust element comprises a rolling bearingcomprising a rotating ring and a non-rotating ring, that is to say afixed ring. The rotating ring is provided with a radial thrust surfaceintended to come into contact with the end of an operating member, suchas, for example, the diaphragm of the clutch.

A non-rotating operating or guide element supports the rolling bearingand, under the action of a control member, for example a mechanical,electrical or hydraulic control member, will axially move the rollingbearing so as to cause the thrust surface of the rotating ring to bebrought to bear axially against the diaphragm of the clutch and thus toactuate the clutch mechanism.

A self-centering or self-aligning sleeve is generally interposed betweenthe non-rotating ring of the rolling bearing and the guide element, thesleeve providing for the connection between these two components while,by virtue of its elasticity, allowing a relative radial movement betweenthem. The rolling bearing can thus move radially so as to beself-centered on the sleeve and thus the guide element.

Reference may be made in this regard to document FR 2,887,311 B1, whichdescribes a clutch release bearing comprising a self-centering sleevecomprising a friction lip configured to rub against the rotating ring.

In certain conditions, angular sliding phenomena between theself-aligning sleeve and the guide element, in particular for examplewhen using a sliding material associated with a weak interface betweenthe sleeve and the guide element or during vibrations. Such sliding candamage the sleeve, thus causing premature wear of the sleeve that couldresult in a radial compensation defect, that is to say the loss of theself-aligning function of the sleeve.

SUMMARY

An aspect of the present disclosure is to overcome these disadvantagesand to improve the clutch release bearings in order to avoid anypremature wear of the self-aligning sleeve.

One embodiment of the present disclosure is a clutch release bearing, inparticular for a motor vehicle, comprising a thrust element having anaxial axis, and a guide or operating element supporting the thrustelement.

The release bearing further comprises a self-aligning or self-centeringsleeve comprising an annular body, for example, mounted in the thrustelement, and a plurality of radial ribs or projections, for example,parallel to the axial axis, extending, for example obliquely, towardsthe guide element from the bore of the body, the free end of each of theribs coming into radial contact with the guide element.

The guide element comprises a tubular part in the form of a bushingdelimited radially by a cylindrical external surface and an internalsurface, the ribs of the self-aligning sleeve bearing radially on theexternal surface of the bushing.

The guide element comprises at least one cutout or opening or axialgroove formed on the cylindrical external surface of the bushing of theguide element and configured to receive a rib of the self-aligningsleeve during angular sliding or rotation of the sleeve with respect tothe guide element.

The cutout makes it possible to immobilize a rib of the sleeve on theguide element in terms of angular rotation, thus reducing premature wearof the sleeve, in particular of the ribs, in the case of angularrotation of the sleeve with respect to the guide element. Integratingthe cutout into the radial demolding of the bushing is particularlyinexpensive. As a variant, such a recess could be machined on theexternal surface of an existing bushing.

The thrust element is advantageously configured to come axially intocontact with an actuating member of a clutch mechanism, such as, forexample, a diaphragm.

The guide or operating element is configured to move translationallyalong the axial axis under the action of a control member of the clutchmechanism, such as a clutch release fork or a hydraulic control piston.

The bushing is, moreover, delimited axially by a radial bearing portionand a free lateral edge, on the opposite side of the radial bearingportion.

The ribs are elastically deformable radially and make it possible forthe thrust element to move radially with respect to the guide elementduring a clutch release operation, so as to allow the self-alignment ofthe rolling bearing with respect to the clutch diaphragm when the axesof rotation of the thrust element and of the diaphragm are not aligned.

What is to be understood by “elastically deformable” is any memberwhich, by virtue of its shape or its material, is capable of deformingin a reversible manner under the action of an external stress exerted onthe member and of adopting its initial shape in the absence of externalstress.

For example, the ribs extend axially over the whole length of the boreof the body, without extending axially beyond the bore.

According to one embodiment, the cutout does not open onto the internalsurface of the bushing. As a variant, there could be provision for thecutout to open onto the internal surface of the bushing, that is to sayto pass radially through the thickness of the bushing.

For example, the cutout has in cross section a parallelepipedal shape,for example a square or rectangular shape, or else a rounded shape.

Advantageously, the bushing of the guide element is made of a more rigidmaterial than the ribs of the self-aligning sleeve.

For example, the bushing is, for example, made of a rigid syntheticmaterial, such as, for example, polymer, an elastomer, or else ofmetallic material, such as steel, or an alloy of metallic materials.

For example, the self-aligning sleeve is advantageously made ofsynthetic material, for example of elastomer or of natural rubber.

According to one embodiment, at least one rib of the sleeve comprises,at its free end, a retaining lip projecting, for example obliquely, fromthe free end towards the body of the sleeve, the retaining lip beingconfigured to form a hook cooperating with the corresponding cutout inthe case of angular rotation of the sleeve with respect to the guideelement.

The retaining lip extends along an axis forming an angle with the bodyof the rib. The angle is here equal to 45°. As a variant, there could beprovision for an angle of between 5° and 45°, for example equal to 30°.

According to one embodiment, the guide element comprises at least threecutouts or axial grooves optionally regularly distributed over thecircumference of the external surface of the bushing.

Two adjacent cutouts are, for example, arranged angularly at 120° to oneanother.

Each cutout is, for example, arranged angularly between two adjacentribs of the self-aligning sleeve.

According to one embodiment, the guide element comprises at least fourcutouts or axial grooves optionally regularly distributed over thecircumference of the external surface of the bushing.

Two adjacent cutouts are, for example, arranged angularly at 90° to oneanother.

Advantageously, the thrust element comprises a rolling bearingcomprising a non-rotating ring, a rotating ring coaxial to thenon-rotating ring, and a row of rolling elements produced, for example,in the form of balls and mounted between the rings, the self-aligningsleeve being secured to the non-rotating ring.

The guide element is preferably an element which is non-rotating withrespect to the rotating ring.

The body of the self-aligning sleeve is, for example, mounted in thethrust element.

The rolling bearing can also comprise a cage for maintaining the regularcircumferential spacing of the rolling elements.

For example, the rolling bearing comprises an annular sealing memberfastened to the rotating ring, in particular to a first axial portion.

For example, the non-rotating ring comprises a toroidal portion havingin cross section a quarter-circle concave internal profile forming atoric raceway for the rolling elements. The toroidal portion isdelimited radially by the raceway and an annular surface forming thebore of the non-rotating ring. The non-rotating ring further comprisesan annular axial portion extending a large-diameter edge of the toroidalportion axially on the opposite side of the rotating ring. The axialportion is extended radially by an annular radial portion extendingradially on the opposite side of the rolling elements.

For example, the rotating ring may comprise a toroidal portion having incross section a quarter-circle concave internal profile forming araceway for the rolling elements. The toroidal portion is delimitedradially by the raceway and an annular surface forming the outer surfaceof the rotating ring. The toroidal portion is extended at each end by anannular axial portion. The first axial portion extends from alarge-diameter edge of the toroidal portion and radially surrounds thetoroidal portion of the non-rotating ring. The second axial portionextends from a small-diameter edge of the toroidal portion axially onthe opposite side of the first axial portion. The rotating ring furthercomprises an annular radial portion extending radially from the secondaxial portion towards the non-rotating ring.

The radial portion of the non-rotating ring can be situated axiallybeyond the end of the first axial portion of the rotating ring. Theradial portion of the rotating ring is situated axially beyond the endof the toroidal portion of the non-rotating ring, on the opposite sideof the radial portion, so as to leave behind an axial space between theinternal surface of the radial portion and the end of the toroidalportion. The cage is mounted axially between the rolling elements andthe radial portion of the rotating ring.

For example, the non-rotating ring may be the inner ring, and therotating ring may be the outer ring radially surrounding the inner ring.

For example, the sleeve may further comprise a sealing member extendingaxially from a lateral edge of the body of the sleeve, on the oppositeside of the radial portion from the non-rotating ring, towards theradial portion of the rotating ring. The sealing member is arrangedaxially in the free axial space existing between the non-rotating ringand the radial portion of the rotating ring.

According to one embodiment, the sealing member comprises an annularsealing lip extending along a direction which is essentially inclined oroblique towards the interior with respect to the axial axis, for exampleby an angle of 45°. The sealing lip can extend axially beyond the sleevein such a way as to come into axial frictional contact with the radialportion of the rotating ring, forming a dynamic seal, in order toprevent the ingress of polluting or contaminating particles between thenon-rotating and rotating rings. The sealing lip is advantageouslyflexible or elastically deformable in the axial direction. The free endof the lip can advantageously have in cross section a triangular or Vshape so as to reduce the friction torque with the rotating ring.

The retaining cage is, for example, arranged radially between thetoroidal portion of the rotating ring and the sealing lip. The sleevecan also comprise a reinforcing member or insert situated in the body ofthe sleeve and comprising a radial portion extending towards the rollingelements and in axial contact with the end of the toroidal portion ofthe non-rotating ring on the opposite side of the radial portion. Theinsert is, for example, made of a more rigid material than the body ofthe sleeve, the ribs and the sealing member. For example, the assemblyformed by the body of the sleeve, the ribs and the sealing member can beovermolded around the insert. As a variant, it is possible for thesleeve not to have such an insert.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood on studying the detaileddescription of the embodiments given by way of non-limiting examples andillustrated by the appended drawings, in which:

FIG. 1 is a view in axial section of a clutch release bearing accordingto one embodiment of the invention.

FIG. 2 is a detail view of FIG. 1 .

FIG. 3 is a view in section along the axis III-III of FIG. 1 .

FIG. 4 is a detail view of the clutch release bearing of FIG. 2 .

DETAILED DESCRIPTION

In FIG. 1 there is shown, in axial section, a disengagement-engagementclutch release bearing device or disengagement-engagement clutch releasebearing 1 comprising a thrust element 10, here a rolling bearing, and anon-rotating operating or guide element 2 supporting the rolling bearing10.

The rolling bearing 10 is configured to cooperate with a clutchdiaphragm 3 shown in FIG. 1 or any member allowing the actuation of aclutch, for example of a motor vehicle. The guide element 2 isconfigured to move translationally along the axial axis X-X under theaction of a control member 4 shown in dotted lines in FIG. 1 , such as aclutch release fork or a hydraulic control piston.

The rolling bearing 10, of axis X-X, comprises a non-rotating inner ring12, a rotating outer ring 14, a row of rolling elements 16, in this casein the form of balls, and mounted between the rings 12, 14 and a cage 18for maintaining the regular circumferential spacing of the rollingelements.

The inner ring 12, of axis X-X, which may be described as a “thin-wallring,” can advantageously be produced by stamping a steel sheet or tube.The inner ring 12 comprises a toroidal portion 12 a having in crosssection a quarter-circle concave internal profile 12 b forming a toricraceway for the rolling elements 16. The toroidal portion 12 a isdelimited radially by the raceway 12 b and an annular surface 12 cforming the bore of the inner ring 12. The inner ring 12 furthercomprises an annular axial portion 12 d extending from a large-diameteredge of the toroidal portion 12 a axially on the opposite side of theouter ring 14. The axial portion 12 d is extended radially by an annularradial portion 12 e extending radially on the opposite side of therolling elements 16.

The outer ring 14, of axis X-X, is coaxial to the inner ring 12. Theouter ring 14, which may be referred to as a “thin-wall ring,” canadvantageously be produced by stamping a steel sheet or tube. The outerring 14 comprises a toroidal portion 14 a having in cross section aquarter-turn concave internal profile 14 b forming a toric raceway forthe rolling elements 16. The toroidal portion 14 a is delimited radiallyby the raceway 14 b and an annular surface 14 c forming the outersurface of the outer ring 14. The toroidal portion 14 a is extended ateach end by an annular axial portion 14 d, 14 e. The first axial portion14 d extends from a large-diameter edge of the toroidal portion 14 a andradially surrounds the toroidal portion 12 a of the inner ring 12. Thesecond axial portion 14 e extends from a small-diameter edge of thetoroidal portion 14 a axially on the opposite side of the first axialportion 14 d. The outer ring 14 further comprises an annular radialportion 14 f extending radially from the second axial portion 14 etowards the inner ring 12.

The radial portion 12 e of the inner ring 12 is situated axially beyondthe end of the first axial portion 14 d of the outer ring 14. The radialportion 14 f of the outer ring 14 is situated axially beyond the end 12f of the toroidal portion 12 a of the inner ring 12, on the oppositeside of the radial portion 12 e, so as to leave behind an axial spacebetween the internal surface of the radial portion 14 f and the end 12 fof the toroidal portion 12 a.

The cage 18 is mounted axially between the rolling elements 16 and theradial portion 14 f of the outer ring 14.

The clutch release bearing 1 further comprises a self-aligning orself-centering sleeve 20 mounted clamped in the bore 12 c of the innerring 12, and an annular sealing member 30 fastened to the outer ring 14,in particular to the first axial portion 14 d.

The self-aligning sleeve 20 is advantageously made of syntheticmaterial, for example of elastomer or of natural rubber. The sleeve 20comprises an annular body 22 mounted in the bore 12 c of the inner ring12 and in radial contact with the bore 12 c. As illustrated, the body 22does not bear axially against the radial portion 12 e of the ring 12. Asa variant, the body 22 could bear axially against the radial portion 12e of the inner ring 12. The sleeve 20 comprises a plurality of radialribs 24 or projections which are parallel to the axial axis X-X andextend towards the interior from the bore 22 a of the body 22 along astraight line forming an angle α with the bore 22 a. As illustrated inFIG. 4 , the angle α is substantially equal to 130°. As a variant, theangle α is between 900 and 135°. In a general manner, the ribs 24 extendsubstantially radially towards the interior, that is to say towards theaxis X-X, from the bore 22 a of the body 22 of the sleeve 20. Asillustrated, the ribs 24 extend axially over the whole length of thebore 22 a of the body 22, without extending axially beyond the bore. Thefree end 24 a of each of the ribs 24 is configured to come into contactwith the guide element 2 of the clutch release bearing device 1associated with the rolling bearing 10. The ribs 24 are elasticallydeformable radially and allow the rolling bearing 10 to move radiallywith respect to the operating element during a clutch release operation,so as to allow the self-alignment of the rolling bearing with respect tothe clutch release diaphragm 3 when the axes of rotation of the rollingbearing 10 and of the diaphragm are not aligned.

What is to be understood by “elastically deformable” is any memberwhich, by virtue of its shape or its material, is capable of deformingin a reversible manner and with the action of an external stress exertedon the member and of adopting its initial shape in the absence ofexternal stress.

The sleeve 20 further comprises a sealing member 26 extending axiallyfrom a lateral edge 22 b of the body 22 of the sleeve, on the oppositeside of the radial portion 12 e of the inner ring 12, towards the radialportion 14 f of the outer ring 14. The sealing member 26 is arrangedaxially in the free axial space existing between the inner ring 12 andthe radial portion 14 f of the outer ring 14. As illustrated, thesealing member 26 comprises an annular sealing lip extending along adirection which is substantially inclined or oblique towards theinterior with respect to the axial axis X-X, for example by an angle of45°. The sealing lip 26 extends axially beyond the sleeve 20 in such away that the sealing lip 26 comes into axial friction contact with theradial portion 14 f of the outer ring 14, forming a dynamic seal, inorder to prevent the ingress of polluting or contaminating particlesbetween the inner ring 12 and the outer ring 14. The sealing lip 26 isflexible or elastically deformable in the axial direction. The free endof the lip 26 can advantageously have in cross section a triangular or Vshape so as to reduce the friction torque with the outer ring 14.

As a variant, the sealing member could comprise two annular sealing lipsarranged radially one above the other. The upper sealing lip couldextend axially beyond the lower sealing lip with the result that theupper sealing lip comes into axial friction contact with the radialportion 14 f of the outer ring 14, forming a dynamic seal, in order toprevent the ingress of polluting particles between the inner 12 and theouter 14 rings. The lower lip would thus make it possible to reduce thequantity of polluting particles directed towards the upper lip.

The retaining cage 18 is arranged radially between the toroidal portion14 a of the outer ring and the sealing lip 26.

The sleeve 20 further comprises a reinforcing member or insert 29situated in the body 22 of the sleeve and comprising a (non-referenced)radial portion extending towards the rolling elements 16 and in axialcontact with the end 12 f of the toroidal portion 12 a of the inner ring12 on the opposite side of the radial portion 12 e. The insert 29 is,for example, made of a more rigid material than the body 22 of thesleeve, the ribs 24 and the sealing member 26. For example, the assemblyformed by the body 22 of the sleeve 20, the ribs 24 and the sealingmember 26 can be overmolded around the insert 29. In a variant, thesleeve does not have to include such an insert.

The additional sealing member 30 is arranged axially on the oppositeside of the sealing lip 26 of the sleeve 20 with respect to the rollingelements 16. The additional sealing member 30 comprises a reinforcementor flange 32 on which there is arranged an internal seal 34 made of aflexible material, more flexible than the flange 32, and configured toexert a dynamic sealing force on the inner ring 12. What is to beunderstood by “dynamic sealing” is sealing between two components havinga relative movement. The flange is made of a rigid material, for exampleby stamping, cutting and folding a steel sheet or tube. Alternatively,the flange 32 can be made of a rigid synthetic material, for example ofpolyamide. The seal 34 is overmolded or vulcanized on a free end of theflange 32. The seal 34 can be made of elastomer, for example of nitrilerubber. The seal 34 comprises an annular radial heel 34 a covering thefree end of the flange 32 and an annular internal sealing lip 34 bextending in a projecting manner from the heel 34 a, respectivelytowards the interior, that is to say towards the rolling elements 16,and towards the exterior of the rolling bearing 10.

The internal lip 34 b is oriented towards the interior of the rollingbearing and extends obliquely downwards. The lip 34 b is flexible orelastically deformable in the radial direction. The free end of the lip34 b can advantageously have in cross section a triangular shape so asto reduce the friction torque with the inner ring 12.

Other shapes are possible for the free end of the lip 34 b, such as, forexample, a V shape oriented towards the interior in the direction of theinner ring 12.

The lip 34 b comes into radial friction contact with the externalsurface of the axial portion 12 d of the inner ring 12 and performs adynamic sealing function with the inner ring 12.

As a variant, there could be provided an external lip extending from theheel 34 a towards the exterior and oriented towards the exterior of therolling bearing, that is to say on the opposite side of the rollingelements 16, and extending obliquely downwards. The external lip isflexible or elastically deformable in the radial direction. The free endof the lip can advantageously have in cross section a triangular shapeso as to reduce the friction torque with the inner ring 12.

As a variant, the seal 34 could also comprise an annular deflecting liporiented towards the exterior of the rolling bearing 10 on the oppositeside of the rolling elements 16. The deflecting lip can extend axiallyin a projecting manner from a radial external edge of the heel 34 a andis situated axially on the opposite side of the internal lip 34 b withrespect to the heel 34 a. The deflecting lip can extend axially beyondthe free end of the first axial portion 14 d of the outer ring 14. Thedeflecting lip would make it possible to reduce the quantity ofpolluting particles directed towards the internal lip 34 b of the seal30. Specifically, when an air flow conveying polluting particles isdirected from the exterior obliquely towards the interior in thedirection of the inner ring 12, the deflecting lip 34 d forms anobstacle that prevents the flow from reaching the internal and externallips 34 b, 34 c.

The lip 26 of the sleeve 20 and the internal lip 34 b of the seal 30 infrictional contact with the outer ring 14 and the inner ring 12,respectively, radially and axially delimit, between the rings, aleak-tight annular space containing the rolling elements 16.

The operating or guide element 2 serves as a support for the rollingbearing 10 by way of the ribs 24 of the sleeve 20. The guide element 2comprises a tubular part in the form of a bushing 5 delimited radiallyby an external surface 5 a and an internal surface 5 b and axially by aradial bearing portion 6 and a free lateral edge 5 c on the oppositeside of the radial bearing portion 6.

The internal surface 5 b or bore of the sleeve 20 is in radial contact,at least in part, with a guide tube 7 of axial axis X-X.

The ribs 24 of the sleeve bear radially on the external surface 5 a ofthe bushing 5.

The radial portion 12 e of the inner ring 12 is in axial frictionalcontact with a first lateral surface 6 a of the radial bearing portion6. The second lateral surface 6 b of the radial bearing portion 6 isintended to be in axial contact with a clutch release member 4, such asa clutch release fork in order to command the axial movement of theclutch release bearing 1.

The radial bearing portion 6 and the bushing 5 can be made in one piece,or in two pieces, with, for example, the radial portion 6 being a metalsheet on which the bushing 5 is overmolded.

The bushing 5 is made of a more rigid synthetic material than the sleeve20, such as, for example, a polymer.

As illustrated in FIG. 3 , and in a no way limiting manner, the body ofthe bushing 5 has through-holes of oblong shape in the circumferentialdirection. Such holes make it possible to reduce the quantity ofmaterial used and the mass of the guide element 2. As a variant, thebody of the bushing could be solid and/or to have other materialcutouts.

In order to compensate for defects in alignment or centering of theclutch release bearing with respect to the diaphragm, the rollingbearing 10 can move radially with respect to the rigid guide element 2,the radial ribs 24 bending to a greater or lesser degree on the bushing5 of the guide element 2. The radial movement is, moreover, guided bythe frictional contact between the radial portion 12 e of the inner ring12 and the radial bearing portion 6 of the guide element 2.

The free lateral edge 5 c of the bushing 5 on the opposite side of theradial bearing portion 6 is provided with an axial retaining member 5 d,for example an annular bead, extending radially towards the outside,that is to say towards the rolling bearing 10, from the external surface5 a of the bushing 5. In the mounted state, visible in FIG. 1 , thesleeve 20, which is secured to the inner ring 12 of the bearing 10, isretained axially with respect to the guide element 2. Thus, the thrustelement formed by the rolling bearing 10 and the sleeve 20 is securedaxially to the guide element 2 while being capable of moving radiallywith respect to the latter.

With the aim of angularly rotationally immobilizing the ribs 24 of thesleeve 20 on the bushing 5 of the guide element 2, the guide element 2comprises one or more cutouts 8 or axial grooves, advantageouslynumbering three. In the example of three cutouts 8, it is advantageousto arrange them at 1200 over the circumference of the bushing 5.

As illustrated, the bushing 5 of the guide element 2 comprises fourcutouts 8, each arranged at 900 from an adjacent cutout on thecircumference of the bushing 5. As a variant, a non-regular arrangementof the cutouts 8 over the circumference of the bushing 5 could beprovided.

The cutouts 8, visible in detail in FIGS. 3 and 4 , are formed on thecylindrical external surface 5 a of the bushing 5 of the guide element2. The cutouts 8 form members for the angular retention of the sleeve 20in the case of angular sliding or rotation of the sleeve 20 with respectto the guide element 2.

The cutouts 8 are regularly distributed over the circumference of theexternal surface 5 a of the bushing 5. Each cutout 8 is arrangedangularly between two adjacent ribs 24 of the sleeve 20.

As a variant, the cutouts 8 may be distributed over the circumference ofthe external surface 5 a of the bushing 5 with an irregular spacing.

In the example illustrated, the cutouts 8 are not through-openings. As avariant, the cutouts could comprise through-openings that extend throughto the internal surface 5 b of the bushing 5.

The cutouts 8 extend axially, for example, over the whole externalsurface 5 a of the bushing 5.

As illustrated in FIGS. 3 and 4 , four ribs 24 of the sleeve comprise afree end 24 a comprising a retaining lip 24 b projecting from the freeend 24 a towards the body 22 of the sleeve 20.

The retaining lip 24 b forms a hook cooperating with the correspondingcutout 8 in the case of sliding of the sleeve 20 with respect to theguide element 2.

The retaining lip 24 b extends along an axis forming an angle β with thebody of the rib 24. The angle β is here equal to 45°. As a variant, theangle β could be from 5° to 45°, for example equal to 30°.

The number of ribs 24 of the sleeve that comprise a free end 24 aprovided with a retaining lip 24 b projecting from the free end 24 atowards the body 22 of the sleeve 20 is optionally similar to the numberof cutouts 8.

Each of the cutouts 8 has a parallelepipedal shape, for example a squareor rectangular shape in cross section, or else a rounded shape.

Integrating the cutouts 8 into the radial demolding of the bushing 5 isparticularly inexpensive.

These cutouts 8 can also be formed after the bushing 5 has been molded,for example by machining, in order to add such a solution to existingguide elements.

The bushing 5 of the guide element 2 is made of a more rigid materialthan the ribs 24 of the sleeve. For example, the bushing 5 is, forexample, made of rigid synthetic material, such as, for example,polymer, an elastomer, or else a metallic material, such as steel, or analloy of metallic materials.

By virtue of the cutouts 8, in the case of the phenomenon of angularsliding or rotation between the ribs 24 of the sleeve 20 and the bushing5 of the guide element 2, the ribs 24 will be inserted into thecorresponding cutout, generating the angular rotational immobilizationof the sleeve 20 with respect to the guide element 2, thereby avoidingpremature wear of the ribs 24 that could result in a defect in terms ofradial compensation, that is to say the function of self-alignment ofthe sleeve.

When the sleeve 20 is being assembled to the guide element 2, the ribs24 provided with a retaining lip 24 b are not necessarily situated in acorresponding cutout 8. During the first angular rotation of the sleeve20 with respect to the guide element 2, the ribs 24 provided with aretaining lip 24 b will be inserted into a corresponding cutout 8.

The ribs 24 provided with a retaining lip 24 b will not disturb theradial movement of the sleeve 20 with respect to the guide element 2.

Representative, non-limiting examples of the present invention weredescribed above in detail with reference to the attached drawings. Thisdetailed description is merely intended to teach a person of skill inthe art further details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the invention.Furthermore, each of the additional features and teachings disclosedabove may be utilized separately or in conjunction with other featuresand teachings to provide improved clutch release bearings.

Moreover, combinations of features and steps disclosed in the abovedetailed description may not be necessary to practice the invention inthe broadest sense, and are instead taught merely to particularlydescribe representative examples of the invention. Furthermore, variousfeatures of the above-described representative examples, as well as thevarious independent and dependent claims below, may be combined in waysthat are not specifically and explicitly enumerated in order to provideadditional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intendedto be disclosed separately and independently from each other for thepurpose of original written disclosure, as well as for the purpose ofrestricting the claimed subject matter, independent of the compositionsof the features in the embodiments and/or the claims. In addition, allvalue ranges or indications of groups of entities are intended todisclose every possible intermediate value or intermediate entity forthe purpose of original written disclosure, as well as for the purposeof restricting the claimed subject matter.

What is claimed is:
 1. A clutch release bearing for a motor vehicle,comprising: a thrust element having an axial axis, a guide elementsupporting said thrust element, the guide element comprising a tubularbushing having a cylindrical external surface and having an internalsurface, and a self-aligning sleeve comprising an annular body and aplurality of radial ribs each having a free end, the plurality of ribsextending towards the guide element from the annular body, wherein thefree ends of at least a first set of the plurality of radial ribsradially contact the cylindrical external surface of the bushing, andwherein the bushing comprises at least one opening formed on thecylindrical external surface that is configured to receive one of theplurality of radial ribs.
 2. The clutch release bearing according toclaim 1, wherein the opening is a blind opening.
 3. The clutch releasebearing according to claim 1, wherein the bushing is made from amaterial having a rigidity greater than a rigidity of the radial ribs.4. The clutch release bearing according to claim 1, wherein the freeends of a second set of the plurality of radial ribs each include aretaining lip projecting from the free end, the retaining lip beingconfigured to cooperate with one of the at least one opening to limitangular rotation of the sleeve relative to the bushing when the secondset of the plurality of radial ribs is located in the at least oneopening.
 5. The clutch release bearing according to claim 4, wherein theclutch release bearing is shiftable from a first configuration in whichnone of the plurality of radial ribs is located in the at least oneopening to a second configuration in which the second set of theplurality of radial ribs is located in the at least one opening.
 6. Theclutch release bearing according to claim 1, wherein the at least oneopening comprises three openings spaced evenly around a circumference ofthe external surface of the bushing.
 7. The clutch release bearingaccording to claim 1, wherein the at least one opening comprises twoopenings separated by 120°.
 8. The clutch release bearing according toclaim 1, wherein the at least one opening comprises at least fouropenings.
 9. The clutch release bearing according to claim 1, whereineach opening of the at least one opening is located angularly between anadjacent pair of the plurality of radial ribs.
 10. The clutch releasebearing according to claim 1, wherein the thrust element comprises arolling bearing comprising a non-rotating ring, a rotating ring coaxialto the non-rotating ring, and a row of rolling elements mounted betweenthe rotating ring and the non-rotating ring, the self-aligning sleevebeing secured to the non-rotating ring.
 11. The clutch release bearingaccording to claim 1, wherein the guide element is non-rotating.
 12. Theclutch release bearing according to claim 1, wherein the opening is ablind opening, wherein the bushing is made from a material having arigidity greater than a rigidity of the radial ribs, wherein the freeends of a second set of the plurality of radial ribs each include aretaining lip projecting from the free end, the retaining lip beingconfigured to cooperate with one of the at least one opening to limitangular rotation of the sleeve relative to the bushing when the secondset of the plurality of radial ribs is located in the at least oneopening, wherein the clutch release bearing is shiftable from a firstconfiguration in which none of the plurality of radial ribs is locatedin the at least one opening to a second configuration in which thesecond set of the plurality of radial ribs is located in the at leastone opening, wherein the at least one opening comprises three openingsspaced evenly around a circumference of the external surface of thebushing, and wherein each of the at least one opening is locatedangularly between an adjacent pair of the plurality of radial ribs.